SNOMED-CT seeks to clarify clinical concepts

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ORLANDO—One of William Shakespeare’s most oft-cited lines from the play Romeo and Juliet, “What's in a name? That which we call a rose by any other name would smell as sweet,” is a beautiful romantic simile; however, multiple names for the same object in healthcare are bedeviling to IT systems. For example, depending on the clinician, a myocardial infarction may be termed a heart attack, an MI, a myocardial infarct, an infarction of the heart, or a cardiac infarction.

The Systematized Nomenclature of Medicine-Clinical Terms (SNOMED-CT)—a comprehensive clinical terminology originally created by the College of American Pathologists—is an on-going effort to define clinical concepts and terminology variants. It is one of a suite of designated standards for use in U.S. federal government systems for the electronic exchange of clinical health information and also is a required standard in interoperability specifications of the U.S. Healthcare Information Technology Standards Panel.

In April last year, SNOMED-CT was purchased by the International Health Terminology Standards Development Organization (IHTSDO), a non-for-profit association in Denmark that maintains and distributes the system.

Maria Hendrickson, a software architect with Philips Healthcare, presented an overview of SNOMED-CT and its utilization for clinical systems in a narrated electronic poster presentation at the 2008 HIMSS conference.

“The terminology is made up of concepts, which is a single unique clear idea such as ‘myocardial infarction,’ and terms, which are alternate labels for the concept such as ‘heart attack,’” she said. “In addition, each concept can belong to multiple parent concepts, such as a pressure sore on the back that will belong to both the ‘disorder of the back’ and ‘pressure sore’ concepts.

“SNOMED-CT covers many aspects of the care process including assessment, planning, implementation, and evaluation,” she said. “It currently contains more than 357,000 concepts and more than 600,000 terms.”

The terminology also is continually evolving, with a twice-yearly distribution of updates to its database.

One of the advantages to using SNOMED-CT in clinical information systems is that it allows for easier searching in data analysis—a critical tool in evidence-based medicine. It also is fully international in its scope. It is used by more than 40 countries and available in Spanish, German, and English versions, with Danish and Swedish versions in progress and a French version in the beginning phases of translation, according to Hendrickson.

The SNOMED-CT terminology also is mapped to a variety of other terminology systems through the National Library of Medicine’s Unified Medical Language System. In addition, medical disease coding systems such as the International Classification of Disease (ICD-9) have mappings available allowing for the interchange of terminologies.

For clinical information system designers, these mappings permit the use of multiple terminologies as an interface for a specific user audience; which can then point to specific SNOMED-CT reference terminology in a manner that is transparent to the user. This enables the utilization of many reference terminologies within one information system, Hendrickson noted.

On an enterprise and global level, SNOMED-CT allows for coded elements to undergo analysis, data to be benchmarked across sites, and the exchange of information among different systems utilizing the Health Level 7 (HL7) language.

“SNOMED-CT is computer friendly, has frequent releases, is extensive in its scope, and is becoming the standard worldwide,” Hendrickson said.